Bacteria Developing at Different Temperatures 241 



while the fluctuation in the numbers of total bacteria, of bacteria 

 growing at 40°, and of B. coli, was less in the Applied 216 than in 

 the canal, the fluctuation in the ratios between these numbers was 

 very much greater. 



Comparing the canal with Applied 219, we find that by adding 

 a small proportion of sewage to the water we have increased our bac- 

 terial content, as shown by higher values on all three determinations; 



table 8. 



Applied 216: Average Monthly Numbers of Bacteria at 20° C, at 40" C, and of B. coli. and 



THE Bacterial Ratios. 



1905 



January . . . . 

 February. . . 



March 



April 



May 



June 



July 



August 



September . . 

 October. . . . 

 November. . 

 December. . 

 Average 



Bacteria 



4o<'-B. coli 



Ratio 



47 

 63 

 SS 

 72 

 59 

 S8 

 47 

 61 

 73 

 64 

 66 

 60 

 60 



but by comparing our ratios we find that we have increased the class 

 of bacteria developing at 40°, in which must be included the disease 

 germs in a much larger proportion than we have increased the total 

 bacterial content. The fluctuation in the numbers of the difi"erent 

 classes of bacteria and the fluctuation in the ratios between these 



table 9. 



Applied 219: Average Monthly Numbers of Bacteria at 20° C, at 40° C, and of B. coli. and 



THE Bacterial Ratios. 



1905 



May 



June 



July 



August 



September. . 

 October .... 

 November. . 

 December. . 

 Average 



Bacteria 



40° -fi. cdi 



Ratio 



67 

 76 

 07 

 48 

 S« 

 58 



<A 

 6s 



